| 1. |
- Boberg, Pelle, et al.
(författare)
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The effect of high temperatures on seed germination of one native and two introduced conifers in Patagonia
- 2010
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Ingår i: Nordic Journal of Botany. - Chichester : Wiley-Blackwell. - 0107-055X .- 1756-1051. ; 28:2, s. 231-239
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Tidskriftsartikel (refereegranskat)abstract
- We examined the effect of thermal shock on the germination of seeds of three conifers, two introduced (Pseudotsuga menziesii and Pinus ponderosa), and one native to Patagonia (Araucaria araucana). Previous research has suggested increased susceptibility to invasions in burnt areas, and therefore, the effect of simulated fire (heat) on seed germination in these native and introduced species was compared. Seeds were heated to two different heat intensities (50°C and 100°C) for 1 or 5 min, which is within the temperature range reached in the upper soil layers during forest fires. Germination tests were then carried out in a growth chamber. The heat treatments had a negative effect on the germination of P. menziesii at temperatures of 100°C, and a negative effect on the germination of P. ponderosa at the temperature of 100°C and the exposure of 5 min. The heat treatments had no affect at all on A. araucana. The species with larger seeds (A. araucana) had higher survival rates after the thermal shocks. Also intraspecific differences in seed sizes possibly point at larger seeds surviving thermal shocks better than smaller seeds. In addition, thermal shock caused a delay in the onset of germination in the two introduced species, while it did not change the time for germination in A. araucana. © The Authors. Journal compilation © Nordic Journal of Botany 2010.
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| 2. |
- Pedersen, Henrik A. E., et al.
(författare)
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On the distinction of Dactylorhiza baltica and D-pardalina (Orchidaceae) and the systematic affinities of geographically intermediate populations
- 2010
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 28:1, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The eastern European Dactylorhiza baltica (Klinge) N. I. Orlova and the western European D. pardalina (Pugsl.) Aver. (= D. praetermissa var. junialis (Verm.) Sengh) are usually considered to have non-overlapping geographic distributions, for which reason it has rarely been realized that they are morphologically similar. They have not previously been thoroughly compared by molecular methods, and no existing flora or revision has convincingly demonstrated that they can be distinguished by morphological characters. In reality, they might be 'political' rather than natural taxa. Prompted by the recent discovery of geographically intermediate populations (in eastern Denmark), originally identified as D. baltica, we have addressed this problem by analysis of morphometric data as well as molecular data from allozyme markers, plastid haplotypes, nuclear ITS alleles and nuclear microsatellites. Dactylorhiza baltica and D. pardalina turned out to be clearly distinguished genetically, and although they are morphologically similar, a few characters were identified that distinguish with 81-85% certainty between the two taxa. Molecular and morphometric data place the geographically intermediate populations in D. pardalina. Both taxa were confirmed to be allotetraploids combining diploid genomes from the D. incarnata s.l. and D. maculata s.l. lineages, and they should therefore be recognized as infraspecic taxa under D. majalis s.l. Thus, D. baltica should be called D. majalis subsp. baltica; D. pardalina is identical with D. praetermissa var. junialis, but the nomenclatural consequences for D. praetermissa, if treated as subspecies under D. majalis, are still unresolved.
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| 3. |
- Ryde, Ulf
(författare)
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Genetic analysis shows that Rubus vikensis is a distinct species with a disjunct distribution
- 2010
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 28:2, s. 246-250
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Tidskriftsartikel (refereegranskat)abstract
- Rubus vikensis A. Pedersen ex G. Wendt (sect. Corylifolii) was recently described from a restricted area in north western Scania, Sweden. In this investigation, I show that the same species occurs also on the Onsala peninsula in northern Halland and on a single locality in the middle of Halland. It has 35 chromosomes in all parts of the distribution area. Moreover, I show by random amplified polymorphic DNA (RAPD) analysis that R. vikensis is a distinct and well-defined species, clearly separated from the morphologically similar R. wahlbergii, with which it shares the chromosome number.
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| 4. |
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| 5. |
- Bakker, Jan P., et al.
(författare)
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Shading results in depletion of the soil seed bank
- 2014
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:5, s. 674-679
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Tidskriftsartikel (refereegranskat)abstract
- To what extent is the decline of characteristic dry alvar species related to the decline in the soil seed bank during scrub encroachment? We recorded the number of flower stems in the vegetation in relation to light attenuation along an encroachment series progressing from open alvar through small gaps inside dense scrub of Juniperus communis (cover of 60%) to intact dense scrub (cover of 100%) on the island of oland, Sweden. This measurement of potential reproduction (number of flower stems) was then compared to the number of species in the soil seed bank at each site along the alvar encroachment series. Scrub encroachment results in light attenuation between and under the shrubs. The total number of flower stems averaged over all species was similar between gaps and open alvar, but that of alvar species was significantly lower in the gaps, indicating that light attenuation could reduce their seed set. Shading in gaps is related to depletion of the soil seed bank and loss of alvar species, particularly those that do not form a persistent soil seed bank.
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| 6. |
- Johansson, Veronika A., et al.
(författare)
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Dust seed production and dispersal in Swedish Pyroleae species
- 2014
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:2, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- Dust seeds are the smallest seeds in angiosperms weighing just about a few micrograms. These seeds are characteristic of most orchids, and several studies have been performed on seed features, fecundity and dispersal of orchid dust seeds. In this study we examine seed features, seed production and seed dispersal in another plant group with dust seeds, the Pyroleae (Monotropoideae, Ericaceae), focusing on six species: Pyrola chlorantha, P. minor, P. rotundifolia, Chimaphila umbellata, Moneses uniflora and Orthilia secunda. Seed production per capsule among these species was in the range between ca 1000 and 7800, and seed production per capsule bearing shoot was in the range between ca 7000 and 60 000. Combining our results with published information on pollen-ovule ratios suggests that these Pyroleae species have a generally efficient pollination system. The most fecund species was P. minor, the only species among the investigated that is probably largely self-pollinating. The investigated Pyroleae species have a seed production comparable to the less fecund orchid species. We studied seed dispersal in the field in one of the species, P. chlorantha. Despite the extremely small and potentially buoyant seeds, the vast majority of seeds are deposited close to the seed source, within a few meters. Further studies on the recruitment ecology of the investigated Pyroleae species are currently under way.
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| 7. |
- Kullman, Leif
(författare)
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Alpine flora dynamics : a critical review of responses to climate change in the Swedish Scandes since the early 1950s
- 2010
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Ingår i: Nordic Journal of Botany. - : Wiley-Blackwell. - 0107-055X .- 1756-1051. ; 28:4, s. 398-408
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Tidskriftsartikel (refereegranskat)abstract
- Reports about changes of alpine plant species richness over the past 60 years in the Swedish Scandes are reviewed, synthesized and updated with data from recent reinventories. Methodologically, this endeavour is based on resurveys of the floristic composition on the uppermost 20 m of four high-mountain summits. The key finding is that the species pool has increased by 60-170% since the 1950s and later. Some of the invading species are new to the alpine tundra, with more silvine and thermophilic properties than the extant alpine flora. Not a single species of the original flora has disappeared from any of the summits. This circumstance is discussed in perspective of widespread expectations of pending temperature-driven extinction of alpine species in an alleged future warmer climate. These progressive changes coincided with distinct warming (summer and winter) since the late 1980s. During a short cooler period (1974-1994), the species numbers decreased and the upper elevational limits of some ground cover species descended. Thus, discernible responses, concurrent with both warming and cooling intervals, sustain a strong causal link between climate variability and alpine plant species richness. Methodologically, plot-less revisitation studies of the present kind are beset with substantial uncertainties, which may overstate floristic changes over time. However, it is argued here that carefully executed and critically interpreted, no other method can equally effectively sense the earliest phases of plant invasions into alpine vegetation.
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| 8. |
- Kullman, Leif
(författare)
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Recent cooling and dynamic responses of alpine summit floras in the southern Swedish Scandes
- 2014
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:3, s. 369-376
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Tidskriftsartikel (refereegranskat)abstract
- Changes in plant species richness on alpine summits in the southern Swedish Scandes were analyzed between 2004/2006 and 2012. This period experienced consistent summer and winter cooling and finalized with a cold and snow rich summer 2012. Re-surveys of these summits had previously documented substantial increases in species numbers in concordance with climate warming since the mid-20th century. Over the present study period, species richness decreased by 25-46%. The majority of lost species were those that had advanced upslope during the previous warm episode. Cooling since the mid 2000s and particularly the unusually short and snow-rich growth period in 2012 caused a floristic retrogression. Taken together with extensive upshifts of many species during previous relative warm decades, recent downshifts highlight the large capability of certain alpine species to track their ecological niches as climate changes. The pivotal importance of unusually late-lying snow in 2012, suggests that snow cover phenology exerts a more direct effect on the composition of the alpine flora than ambient temperatures. Dynamic modeling of future ecological landscape evolution needs to consider episodes of the kind reported here.
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| 9. |
- Lidén, Magnus, 1951-, et al.
(författare)
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Studies in Dactylicapnos (Papaveraceae-Fumarioideae) part II. Revision of Dactylicapnos sect. Pogonosperma sect. nov., with D. arunachalensis sp. nov.
- 2014
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 32:2, s. 176-184
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Tidskriftsartikel (refereegranskat)abstract
- Dactylicapnos sect. Pogonosperma Liden & M. K. Pathak sect. nov. is established and revised based on morphology, and found to include four species: D. gaoligongshanensis from west Yunnan, D. arunachalensis Liden & M. K. Pathak sp. nov., endemic to central Arunachal Pradesh, D. grandifoliolata (syn. D. ventii) and D. paucinervia (K. R. Stern) Liden & M. K. Pathak comb. nov., the two latter species widespread in the east Himalayas.
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| 10. |
- Lidén, Magnus, 1951-
(författare)
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Three new species of Dactylicapnos (Fumariaceae) and a synopsis of the D. macrocapnos complex
- 2010
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Ingår i: Nordic Journal of Botany. - : Wiley. - 0107-055X .- 1756-1051. ; 28:6, s. 656-660
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Tidskriftsartikel (refereegranskat)abstract
- The Dactylicapnos macrocapnos complex is revised, and D. platycarpa Liden, D. odontocarpa Liden and D. macrocapnos subsp. echinosperma Liden are recognised as new taxa. The complex consists of a chain of 4 vicariant taxa from northwestern India (Garhwal) to western Bhutan (Thimphu). Dactylicapnos cordata Liden (eastern Nepal, Darjeeling) is described and contrasted with its close relative, the geographically disjunct D. burmanica (western Yunnan, Burma).
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